Keyboard Trouble! My z, x, c, v keys work only intermittently.

13" MacBook Core Duo, Mid 2007 A1181 (white plastic case) that I would like to find out why the z, x, c, v keys only work sometimes. Do you think it is a keyboard or logic board problem? I have cleaned the press downs under the keypads for these letters (no help) and I am able to generate these key presses using the keyboard viewer. No known water damage...

If keyboard / top case change is in my fixit future, I hear that the configuration of the top-row fn keys and the color of some internal connector wires are an important consideration in finding the correct replacement part. Is this true?

Source for correct replacement part?

First time posting, all (non-flame) thoughts appreciated!

Thanks in advance.